From: ebiederm@xmission.com (Eric W. Biederman)
To: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Andrew Morton <akpm@osdl.org>,
linux-kernel@vger.kernel.org,
"Paul E. McKenney" <paulmck@us.ibm.com>,
Ingo Molnar <mingo@elte.hu>, William Irwin <wli@holomorphy.com>,
Roland McGrath <roland@redhat.com>
Subject: Re: [PATCH] task: Make task list manipulations RCU safe.
Date: Tue, 14 Mar 2006 13:15:27 -0700 [thread overview]
Message-ID: <m1mzfslr4w.fsf@ebiederm.dsl.xmission.com> (raw)
In-Reply-To: <44170AD3.35031A67@tv-sign.ru> (Oleg Nesterov's message of "Tue, 14 Mar 2006 21:26:27 +0300")
Oleg Nesterov <oleg@tv-sign.ru> writes:
> "Eric W. Biederman" wrote:
>>
>> Oleg Nesterov <oleg@tv-sign.ru> writes:
>>
>> > Some questions.
>> >
>> > first_tgid:
>> > ...
>> > for (; pos && pid_alive(pos); pos = next_task(pos))
>> >
>> > I think this patch makes this 'pid_alive(pos)' unneeded?
>>
>> Close. The problem is that we could have slept with the
>> count elevated on start before we do rcu_read_lock().
>
> Yes, we could have slept. But (unlike next_tgid) this loop
> starts from pos=init_task or from pos=find_task_by_pid()
> and we are doing find_task_by_pid under rcu_read_lock() ?
Yes. We are sorry. The bits of code blurred in the discussion.
Eric
prev parent reply other threads:[~2006-03-14 20:17 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-03-08 16:42 Eric W. Biederman
2006-03-14 17:36 ` Oleg Nesterov
2006-03-14 18:06 ` Eric W. Biederman
2006-03-14 18:26 ` Oleg Nesterov
2006-03-14 20:15 ` Eric W. Biederman [this message]
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